The invention relates to a boiler stoker, especially to the grate of horizontal circulating burning-up combustible material.
At present, the grates for stoker-fired boiler can be classified in structure into two kinds, i.e. the reciprocating grate and the chain grate. The fuel is fed continuously from one end of the grate surface and travels horizontally across the grate to the opposite end as it burns. The residual ash is discharged from the opposite end. The above mentioned stoker grates have the following defects: 1) the coal is ignited mainly by means of the heat radiation from the furnace arch, the ignition begins from the upper layer towards the lower layer of the coal bed in a direction which is opposite to the direction of air flow, the upwards air flow counterworks the downwards transmission of coal ignition, resulting in an unfavorable burning state, cause incomplete combustion and unable to burn the low grade coal; 2) the resident time of coal burning on the grate can not be long as the grate has a limited length, so the coal can not be fully burn up; and 3) the bottom layer of the coal is ignited at last, resulting in the fine coal particles to leak out from the vent slits of the grate and cause a big loss of coal.